Every Dunder Method in Python(pythonmorsels.com)

  class C:
      ...

      def __add__(self, other: C):
          ...

  class C:
      ...

  algebraic_structure Monoid<C>:
     def +(fst: C, snd: C) -> C:
         ...

  class Datetime:
      ...

  class Timedelta:
      ...

  algebraic_structure AffineSpace<Datetime, Timedelta>:
      def point_minus(fst: Datetime, snd: Datetime) -> Timedelta:
          ...
 
      def vector_add(fst: Timedelta, snd: Timedelta) -> Timedelta:
          ...

      def vector_inverse(vec: Timedelta) -> Timedelta:
          ...